1. Field of Invention
The present invention is relates to a die used for vacuum casting.
2. Description of the Related Art
One of the reasons for variations in quality of die cast products and the resultant drop in reliability is gas contained in the die cast products. That is, molten metal injected and filled at a high speed and high pressure forms turbulence inside the injection sleeve and die cavity resulting in entrainment of air or vaporized release agent coated on the die.
To overcome this disadvantage, there is known the technology of casting using a die casting machine using the vacuum die casting method so as to suppress entrainment of gas in the die cast products and thereby reduce variations in quality due to the content of gas in the die cast products (for example, see U.S. Pat. No. 2,785,448).
In a die casting machine using the vacuum die casting method, the die cavity has to be able to be made greater in vacuum and the reduced pressure state maintained in order to cast a high strength and quality product. If the die cavity is not made high in vacuum, the cast product may contain gas. As a result, when applying annealing or other heat treatment to the product after casting, the product will easily suffer from distortion or deformation and it will be difficult to obtain a sufficient effect by the vacuum die casting method.
Japanese Unexamined Patent Publication (Kokai) No. 2002-239705 discloses technology for obtaining a better vacuum in the die cavity and maintaining the reduced pressure state by seamlessly and continuously sealing the mating faces around the cavity.
Summarizing the disadvantages to be solved by the invention, when a casting product has recesses or hollow parts which cannot be molded in the opening/closing direction of the die, it is necessary to insert a so-called slide core between the dies for casting. The slide core inserted between the dies before casting is pulled out in a direction along the mating faces of the dies after casting, then the casting product is taken out from the dies. When using a slide core for vacuum casting and moving the slide core, it is necessary to prevent the slide core from interfering with the seal member. Therefore, the seal structure around the slide core becomes complicated and the reliability of the seal performance easily falls.